Enzymes are being increasingly used as catalysts in chemical and biochemical synthesis. Thus, hydrolases, especially lipases (EC 3.1.1.3), are already being used in many industrial lipolysis processes by virtue of the often milder reaction conditions.
Suitable enzymatic esterification or transesterification processes are described, for example, in K. Drauz and H. Waldmann, Enzyme Catalysis in Organic Synthesis, VCH-Verlag, Weinheim 1975.
It is known that transesterifications in water-free or substantially water-free media are catalyzed by lipases. If water is also present in the reaction system of esters, alcohol and lipases, the elimination of bound acids to free acids normally occurs. Since various lipases also catalyze the formation of esters from free fatty acids and alcohols, a transesterification reaction with an acid intermediate stage is ultimately carried out in the majority of cases in addition to a direct transesterification. For many industrial processes, however, the formation of free acids in the system is a major disadvantage. The water content partly prevents an industrially and commercially acceptable conversion (formation of an nfavourable thermodynamic equilibrium). Expensive industrial equipment has to be used to obtain satisfactory yields (removal of water, for example, by azeotropic distillation, membrane separation processes, vacuum distillation).
The disadvantage of enzyme-catalyzed reactions often lies in the availability and stability of the functional proteins involved in the process. Enzymes stabilized by immobilization, for example by microencapsulation, which can be used for a variety of applications are already known from the prior art.
The reaction of hydrophobic compounds can be carried out by the use of water-in-oil (w/o) microemulsions, as described by Orlich and Schomaeker in Enzyme Microb. Technol.; 2001; 28; 1; 42-48 for the lipase from Candida rugosa. However, the concentration of water in the solution and the composition of the components of the w/o microemulsions are very critical to the success of the reaction.
Accordingly, the problem addressed by the present invention was to provide a system for enzyme-catalyzed reactions in which the substrate concentrations could be varied while the interfaces and hence the concentration of oil and water would remain constant to the extent that they would not have a major influence on the reaction or on the activity of the enzyme. In addition, these systems would be inexpensive and recyclable.